关键词: 烟草, 钾离子通道, 基因克隆

Abstract: Potassium channels have important physiological roles in plants. This study obtains a potassium channel gene from the tobacco variety K326 by using homologous cloning strategy. Sequences analysis showed that this gene contains 1 989 bp and encodes a protein consisting of 662 amino acids, the calculated molecular mass was 75.6 ku and the theoretical isoelectric point (pI) was 7.2. Homology analysis suggested that the gene had a high homology with the potassium channels KAT3 of both Nicotiana tomentosiformis and Nicotiana sylvestris, so it was named as NtKAT3. Protein structure and function analysis showed that NtKAT3 has 5 transmembrane domains, which was a hydrophobic membrane protein. Expression patterns analysis showed that the highest expression level was observed in the roots, followed by leaves, stems and flowers. Under low potassium condition, the expression level of NtKAT3 in tobacco seedlings increased firstly and then decreased, the highest expression level of NtKAT3 appeared at 12 h, and the lowest level appeared at 48 h. Under 200 mmol·L^-1 NaCl treatment, NtKAT3 reached the lowest expression level at 6 h, while the highest level appeared at 24 h, which indicated that the gene NtKAT3 can be induced by low potassium or salt stress.

Key words: tobacco, potassium channel, gene cloning